FURTHER STUDIES OF THE REACTIONS OF DITUNGSTEN HEXA-t-BUTOXIDE WITH ACETYLENES. ISOLATION AND CHARACTERIZATION OF WO(OCMe3)4(THF), 2 AND W(CPh)(OCMe3)3

Article abstract of DOI:10.1016/0022-328X(85)80338-7

Further studies of the reactions of W2(OCMe3)6 with acetylenes at 70 deg C in toluene for up to 12 h are reported.All acetylenes of the type PhCCR afford (Me3CO)2W(μ-CPh)2W(OCMe3)2 (1) in high yield.Purely aliphatic acetylenes, RCCR, give complex products containing tritungsten cluster units, one example from the reaction with 4-octyne being the dimer of trimers 2 (3b), whose structure has been determined by X-ray crystallography.It forms monoclinic crystals (P2₁/n) with unit cell dimensions of a 12.838(1), b 14.440(1), c 18.465(1) Angstroem, β 97.57(1) deg, and Z = 2.One half of the centrosymmetric dimer is the crystallographic asymmetric unit and it contains an approximately isosceles triangle of metal atoms (W-W 2.892(1), 2.901(1), 2.418(1) Angstroem) with one of the longer edges bridged by CC3H7 and the other by μ-O.There are then five terminal OCMe3 groups and the two trinuclear units are united by a pair of bridging oxygen atoms.From the reaction of W2(OCMe3)6 with 4-octyne it was also possible to isolate the mononuclear complex WO(OCMe3)4(THF) (4) as colorless or pale yellow crystals.The structure, which is disordered, was determined by X-ray crystallography and contains molecules with apparent C₄ symmetry.The four Me3CO groups form a planar set of W-O bonds (1.905(8) Angstroem) and the W=O and W-OC4H8 bond lengths are 1.77(3) and 2.38(3) Angstroem), respectively.The refinement was conducted in space group I4 with Z = 2 and unit cell dimensions of a 11.707(1) and c 9.514(a) Angstroem.Aliphatic carbynes, (Me3CO)3W<*>CR (R = Et, Pr), upon reactions with W2(OCMe3)6 in 1/1 ratio gave the dimer of trimers product (3), but the aromatic carbyne, (Me3CO)3W<*>CPh, did not give the dinuclear species 1.The structure of W(CPh)(OCMe3)3 (5) was determined by X-ray crystallography.It forms monoclinnic crystals (P2₁/n) with unit cell dimensions a 10.011(3), b 21.041(7), c 10.064(2) Angstroem, β 94.66(2) deg and Z = 4.The tungsten atom has nearly regular tetrahedral coordination with W<*>C 1.758(5), W-O(mean) 1.865(4) Angstroem, O-W<*>C(mean) 107.8(11), W-O-C(mean) 141(1) and W<*>C-C 175.8(4) deg.